Abstract

Mangroves and seagrass beds are important fish habitats, but little is known of their nursery function and their connectivity to other habitats such as coral reefs. Here, the present state of knowledge on connectivity between non-estuarine mangroves/seagrass beds and coral reefs by post-larval coral reef fishes is discussed. Only since the year 2000 substantially more (indirect) evidence has been obtained for such connectivity. This has largely been based on studies quantifying juvenile/adult fish densities in these habitats to deduce ontogenetic migrations. Almost all studies have been done in the Caribbean, and they are practically absent for the much larger Indo-Pacific region. Although various fish species are found as juveniles in mangroves and seagrass beds only few (especially members of Lutjanidae and Haemulidae) appear to show a high (obligate) dependence on these habitats. The effects of absence of mangrove and/or seagrass habitats on fish densities of juvenile and adult fishes will be discussed, which is particularly relevant for marine conservation and MPA design. Also, studies will be discussed which have investigated the effect of habitat size and distance to nursery habitats on the adult fish population on coral reefs. Little direct evidence of connectivity is currently present, but with new or advanced techniques currently available, such as laser-ablation ICPMS and tagging with micro-tags or transponders, it is possible in the near future to advance our understanding of the biological connectivity between these tropical coastal ecosystems

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